1. Field of the Invention
The present invention relates generally to a luminaire. More particularly, the invention relates to a luminaire having an occupancy sensor causing demand response bi-level illumination of light emitting diodes (LEDs).
2. Description of the Related Art
Bollards are protective structures which are generally located around buildings or machines at industrial, commercial, or institutional premises. They are believed to be named because their shape tends to resemble posts or “bollards” used at wharfs, and around which mooring lines are fastened. Bollards are generally known as having cement or extruded metal posts to protect an exterior portion of a building or the like. When metal bollard posts are utilized, they may be fastened to structures already placed in the ground or cemented into place, or alternatively filled with cement.
In many instances, the bollard structures are utilized to provide lighting over a preselected area. In some instances, the bollard luminaires provide illumination in a selected direction in order to illuminate a structure which the bollard protects. The bollards are generally known to have domes or other upper casting portions, and multi-tier louvers, or a combination of both.
One problem with existing bollard luminaires is their inefficient use of energy. Existing luminaires are typically on at a high level of illumination for several hours at a time. However, during many of these hours, people are not present, and therefore the high level of illumination is not necessarily needed, where a lower level of illumination would suffice. When examining whether sensors could be utilized with existing bollard designs to sense occupants in the area of the bollard and change the illumination level from a low level to a high level. One problem was the use of sensors which require an unobstructed “view” of the area surrounding the bollard. In order to provide such “view,” the sensor had to be placed outside of the bollard, which was detrimental to the aesthetic quality of the bollard. Moreover, a lens needed to be placed over the sensor to try to inhibit vandals who may have attempted to break or steal the sensor. Thus, a bollard design is needed which does not require the sensor to be placed outside of the bollard, and which therefore retains the aesthetically pleasing qualities of the bollard, without inhibiting the utility of the sensor.
Another problem with the existing bollard design is that existing lamp systems are not as efficient as newer forms of lighting, such as light emitting diodes (LEDs) which can emit an equivalent amount of light with less power usage. Additionally, it would be preferable to incorporate the LED technology in such a way as to render the lighting modular so that banks of light could be replaced as they deplete or become less efficient. Alternatively, it would be preferable to easily replace the banks of light as newer lighting technology becomes available without need of replacing the entire bollard assembly.
Given the foregoing, it will be appreciated that a luminaire is needed which has improved efficiency over existing luminaires, which allows for easy replacement of the lamp structures and which also utilizes a sensor which is enclosed within the luminaire housing.